So-called quantum counting detectors are known for the quantitative and energy-resolved determination of quantum absorption events. These detectors can detect quanta of X-ray or gamma radiation incident on the detector in terms of their number and energy. These detectors generally include a converter layer for converting a quantum absorption event that takes place in the converter layer into electrical charges. In this case, the converter layer can be produced e.g. from a semiconductor material. A cover electrode is applied on a first surface of the converter layer and a multiplicity of individual electrodes arranged in matrix-like fashion are applied as counterelectrodes with respect to the cover electrode on a second surface opposite the first surface. The cover electrode and individual electrodes are also known by the designations “rear side contact” and “pixel contact”, respectively.
During operation of the detector, a voltage is applied between the cover electrode and the individual electrodes, whereby electric fields form in the converter layer. A detector pixel is formed by each pixel contact and the electric field assigned thereto. Electrical charges generated in the active region of the electric fields of the detector pixels as a result of e.g. one or more quantum absorption events are separated from one another in the converter layer and accelerated—depending on charge type—to the cover electrode or to respective pixel contacts. The charges moved in this way influence currents to the corresponding electrodes. On the basis of these electrical signals it is possible to determine the number of quantum absorption event(s), that is to say the number of absorbed quanta of the X-ray or gamma radiation, and an energy assigned to them. One disadvantage of conventional quantum detector modules is that the number and/or energy cannot be determined with satisfactory accuracy.